Back to EveryPatent.com
United States Patent | 5,550,103 |
Motowidlo ,   et al. | August 27, 1996 |
A method of producing a high temperature long length coil of superconductor wire or tape having improved critical current densities by utilizing an in-line pressing operation to heal the microcracks in the tape or wire which were introduced in rolling and coiling operations. The material can be Bismuth-2223, Bismuth 2212, Thallium-1234 or any other high temperature superconducting material. In the case of the Bismuth-2223, an improved "powder-in-tube" processing operation is provided to utilize excess bismuth, calcium, and copper in the initial composition material, and forming a partially developed Bi-2223 phase in the precursor powder introduced into the silver tubes. The final product has a 90-100% Bi-2223 phase with fine dispersions of secondary phases, to provide improved flux pinning thereby improving the critical current density of the material.
Inventors: | Motowidlo; Leszek (Bristol, CT); Haldar; Pradeep (Guilderland, NY) |
Assignee: | IGC/Advanced Superconductors, Inc. (Waterbury, CT) |
Appl. No.: | 108929 |
Filed: | August 18, 1993 |
Current U.S. Class: | 505/430; 505/432; 505/433; 505/704; 505/705 |
Intern'l Class: | H01B 012/04; H01B 013/00 |
Field of Search: | 505/1,430,432,433,705,704 |
4906609 | Mar., 1990 | Yamauchi | 505/1. |
5004722 | Apr., 1991 | Tallman | 505/1. |
5057488 | Oct., 1991 | Arendt | 505/1. |
5221663 | Jun., 1993 | Assmann | 505/1. |
Foreign Patent Documents | |||
5-135635 | Jun., 1993 | JP | 505/433. |
Haldar, Pradeep et al., "Enhancement in Critical Current Density of Bi-Pb-Sr-Ca-Cu-O Tapes by Thermomechanical Processing: Cold Rolling Versus Untaxial Pressing" Applied Physics Letters, vol. 60, No. 4, Jan. 27, 1992, pp. 495-497. Shibuta, Nobuhiro et al. "Transport Critical Current Properties of Silver-Sheathed B. Based Superconducting Tapes and Coils at 4.2K" Japanese Journal of Applied Physics, vol. 30, N. 12B, Dec. 1991, pp. L2083-L2084. Fukiger, R. "The Deformation of B (223) Tapes by Hot Rolling" High Temp. Superconductivity Spring Symposium, Apr. 12-16, 1993. Halder et al, "Bulk Superconductivity at 112K in Tl(Ba,Ca).sub.2 Ca.sub.3 Cu.sub.4 O.sub.10.5+.gamma. with Four Consecutive Copper Layers", Science, vol. 241, Sep. 2, 1988, pp. 1198-1200. |